Haven't seen a production environment iPad program without MDM oversight. It is basically required to keep the iPad in a certified state and therefore a prerequisite, at least in airlines, to satisfy the authorities requirements. But, as Intrance said, it still requires data updates within the apps themselves.
Not only in theory, but also in practice one can update three apps at the same time if necessary, two in split screen (if the apps allow that) and one in slide over. It gets kinda crowded on the screen though, especially in the 10 inch (small) variants, much easier and better on the 13 inch ones but i haven't seen an airline issue those yet. Nor have i really seen the need for that.
Airbus actually does an update of all its different apps (W&B, take off performance, inflight performance, landing performance, OLB, QRH) with inter-app communication and it usually works quite well. And is very fast indeed, takes all of 20 to 30 seconds, so not really onerous on the users time.